Valve guide and seat in one.

[DaveRC]

Valve guide and seat in one.

I have been working on an Upsher vertical, photos and details on progress to come soon, and been working on the head. I have it almost done and ready for the valve guides, which I was turning in bronze, but then bumped into a friend of mine that has very successfully made several engines.... Now, looking at the plans he made a suggestion, which I have started to work on, just would like to see if anyone else has done this.

He suggested I make a sleeve up, so it is the valve guide and seat in one, make the hols a bit bigger in the head and insert the whole thing and then re-drill the inlet (or out on the other) after its in place. I made one last night out of the bronze I was using and it's looking good (not touched the head yet) but one thing doing it this way has aloud me to to is cut the valve seat on the lathe rather than make a tool. I will make the other and the valves all up before I even think about drilling out the head.

But so far it looks like a real good idea, any thoughts.......?


Dave

 

[Brian Rupnow]

Look at the thread I have about building the Kerzel engine. What you are referring to are called valve cages. There is a lot of info about them on my Kerzel thread.

 

[jonesie]

i used valve cages on my powerhouse an have then made for my farmboy and they have worked out real good. jonesie

 

[Brian Rupnow]

Hundreds, if not thousands of amateur machinists have succesfully built small i.c. engines without resorting to valve cages. They are not really necessary, but if you screw up wih the original valve/seat interface like I did with the Kerzel engine, the valve cages give you a second chance without scrapping the head.

 

[DaveRC]

Hi Brian,

Found your post on the valve cage (page 25 if anyone else is looking) and now I know what they are called I can look for more information.

To me they seems like a great idea that these can be made outside the head so if you do mess one up you don't have to start again, the thought of remaking the head I have just done after cutting all the cooling fins just makes me shudder...

Thanks for the info,

Dave

 

[cfellows]

The first gas engine I ever made I just cut the valve seat and guide into the cast iron head. I guess it was beginner's luck that it worked fine the first time. However, I would never do it that way again. Valve cages just make more sense on so many levels.

Chuck

 

[Metal Butcher]

Hi Dave. What a coincidence. I'm about to install my first set of valve guides and cut the valve seats today. I too was tormented with the idea of simply drilling and reaming a full length (cage) valve guide and cutting valve seat in one set up. To me this seemed to be a sure-fire method that had to work. I didn't understand the need to complicate things by making a valve seat cutter. It just didn't make any sense.

So why did I bother? It took quite a bit for me to get it through my thick skull that drill bits will more often than not wander slightly off center. In some off the more severe cases this can be seen with the naked eye at the exit point of a drilled and reamed hole. But In most cases this goes unnoticed and has no ill effect on most parts that are turned, drilled, and reamed in one set-up. Valves are different, they need to be dead on to seat and seal every time.

You could try it to see if luck will prevail. If not than you will have the problem and difficulty of removing and replacing the pressed in or locktited in cages, and starting all over again with no guarantee that the next one will work.

I asked myself why would Experienced Builders bother to make a valve seat cutter, and why would Hamilton specify making and using a valve seat cutter in his plans?. Surely they all understand the concept of completing all possible machining steps in one set-up?

-MB

 

[DaveRC]

Hmm, interesting answers, and can see the arguments.

I do like the concept of the valve cages and I could see two ways to go to make this work

One, and this was something I was going to do, with the cage out the head and the valve made I could spend a lot more time and it would be a lot easer to lap in the valve, I was even thinking of leaving a stud on the top on the valve I could attach the dremmal to to lap it in, once done pop it back in the lathe and turn it off. At least this way you should be able to make sure the valve is bedded in properly before you fit it into the head.

The second method, is one that I just thought of, don't cut the seat in the lathe, still make the seat cutting tool and use that, ok, seems a bit daft but does give you the option of if you stuff it then it's still not a new head that is needed.

Dave

 

[Brian Rupnow]

DaveRC ---Based on everything I have ever seen, heard, or learned about lapping valve faces, using a power tool to do it is an absolute no-no. It is done manually. with finger pressure, and a back and forth rotation of the stem.

 

[Metal Butcher]

Dave, try this experiment.

Chuck up a piece of brass or aluminum in your lathe roughly the diameter of the proposed valve cage. True up the O.D. with a light cut. Drill and ream a 3/32" through hole for a precision fit rod. Cut it off at the same length of the valve cage. Cut a piece of the 3/32 rod half an inch (or more) longer that the reamed cylinder.

Now, set up a tenths indicator on a check stand. And indicate on the protruding rod sticking out both ends while you rotate the simulated 'cage'.

Let us know your findings.

-MB

 

[DaveRC]

OK, I can see where this is going....... and even before I start I got a good idea what is going to happen. I did ask for advice and should listen to it.....

I have a day at home tomorrow and most of that will be spent in the shop, so will be having a very good look at this again. I think I was getting frustrated when trying to make the valve guides and the bronze I have is a pig to turn, so I will try making the guides in brass, if these go OK then I will stick with the original plan and will be making up a seat cutter.....

Also may have time to start uploading my progress on here.....

Thanks again,

Dave

 

[Groomengineering]

Hi Dave. Here's one I started several years ago,

Made pretty good progress until I messed up the valve seats. So it's cages or a new head, and it was relegated to the 'when my skill level increases' shelf. I will be making a piloted seat cutter regardless of which way I go. If there's one thing I've learned over the past few years it's that the right tool makes everything so much easier (and a lot less :wall: )

Cheers

Jeff